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Key Takeaways

  • Firm approaches to putting greens improve the golfer experience.
  • Extending cultural practices that produce firm putting green conditions out into the approaches will improve firmness there as well.
  • Some cultural adjustments will improve firmness quickly, while others will take more time to yield benefits.
  • If cultural practices alone aren’t delivering the desired results, adding drainage and/or replacing the rootzone material can significantly improve approach firmness and ball reaction.
  • Sand capping approaches will not necessarily lead to firm conditions. Sands that are too round or narrowly graded are likely to play soft regardless of how well the approaches are maintained.
     

A positive trend in golf course design, renovation and maintenance is trying to make golf more fun. Examples of how courses have increased the fun factor include reducing the number and size of bunkers, removing trees, widening fairways, building forward tees, maintaining rough at a lower height, and expanding and firming approaches to putting greens.

Soft approaches discourage or prevent approach shots from bouncing and running up onto putting surfaces. One of the most difficult and frustrating shots in golf is the approach shot to a firm green with a soft approach. Furthermore, soft, spongy approach turf is difficult to hit pitch and chip shots from. Many golfers have a lower-trajectory ball flight and tend to come up short on approach shots, so soft approaches can be a double whammy that keeps them from reaching greens and makes their chip shots even harder. At the same time, players of all skill levels like to have shot options into and around the greens and soft approaches may eliminate the use of the ground game. Firmer approaches improve the playability and interest of the golf course for all players, but it takes planning and consistent attention to deliver these conditions.

This article is divided into two parts. Part one will evaluate the cultural practices courses can use to firm-up approaches and part two will provide guidance on more aggressive improvement projects that can change how approaches play and perform. Before we delve into improvement strategies, let’s first understand why approaches are often soft and spongy. The most typical reasons for such conditions are listed below:

  • Elevated amounts of thatch and organic matter
  • High height of cut (HOC)
  • Excessive grain and lateral growth
  • Overwatering due to overlapping irrigation coverage
  • Lack of drainage
  • Sand capping with the wrong sand
  • Excessive aeration
  • Use of lightweight mowers
  • Absence of rolling
     

Elevated thatch and organic matter levels, excessive irrigation and lack of adequate drainage are the most common reasons for soft approaches. We will discuss strategies to improve these and other issues below.

Part 1 – Maintenance Practices to Improve Firmness

This first section includes recommendations for cultural practices to improve approach firmness. These practices can substantially increase firmness. Some will deliver almost immediate results, like adjusting sprinkler patterns, while others will require a strong commitment over a minimum of two full growing seasons to see quantifiable benefits. It takes time to build up thatch and organic matter. It typically takes even longer to reduce elevated organic matter levels without very disruptive measures.

Thatch and Organic Matter Management

Managing thatch and organic matter in approaches can be labor intensive, but routine practices will pay off over time. Here are the top recommendations to reduce thatch and organic matter in approaches:

  • Treat the approaches as extensions of the greens. Extend putting green cultural practices out into the approaches as much as possible.

  • Aerate approaches just as you do the putting greens and follow with ample sand topdressing. Approaches can accept greater topdressing rates due to the higher HOC.

  • Don’t over-aerate. Surface conditions soften following aeration and the amount and frequency of aeration can be overdone. Don’t aerate approaches within six to eight weeks of a major event and don’t aerate so aggressively and so often that the surface is destabilized.

  • Conduct routine vertical mowing three or four times per month during the optimal growing season. Deep vertical mowing at depths from 0.75 to 1.50 inches once or twice annually may be necessary as well.

  • Apply sand topdressing one to four times per month during the optimal growing season. Apply higher rates than on greens given the higher HOC on the approaches. A good guideline is to apply 2,500 to 4,000 pounds of sand per 1,000 square feet per year, depending on the length of the growing season.

  • Utilize a widely graded sand. Consider using finer sands for at least a portion of the year to increase the particle size distribution. Be sure to conduct a physical soil analysis of any potential sand materials before topdressing. Sands that are too narrowly graded or too round will not provide firm conditions.

  • Fertilize and irrigate only enough to meet the turf demands. Limiting nitrogen inputs and soil moisture will mitigate excessive organic matter production.

  • Finally, test for organic matter in the top 1 inch annually to monitor progress.
     

Height of Cut

The higher the HOC, the more plant tissue there is to absorb an inbound golf shot and reduce the bounce. Additionally, a high HOC may reduce the variety of golf shots available to players who come up short of the green. Lowering the HOC is a relatively simple way to improve bounce and roll in the approaches and the benefits will be noticeable in a short amount of time. Here are a few key considerations regarding HOC in approaches:

  • Maintain a low HOC when the turf is healthy and growing vigorously.

  • The lower the HOC, the smoother the surface and better the ball roll. A lower HOC also increases firmness because there is less vegetation to soften the impact of an inbound golf ball.

  • Here are suggested HOC ranges in inches for approaches based on grass type:
    • Creeping bentgrass – 0.180 to 0.250
    • Kentucky bluegrass – 0.350 to 0.500
    • Perennial ryegrass – 0.250 to 0.400
    • Poa annua – 0.250 to 0.400
    • Hybrid bermudagrass – 0.200 to 0.400
    • Seashore paspalum – 0.300 to 0.450
    • Zoysia matrella – 0.200 - 0.300
    • Zoysia japonica – 0.400 - 0.500
       

Managing Grain

Leaves and stems growing horizontally along the surface cause grain. Grain in bermudagrass and bentgrass varieties can be especially problematic if not managed in approach areas. When there is lots of lateral growth, inbound golf shots that land into the grain may not bounce and roll forward as they would with little grain or down grain. Additionally, amateurs and even the pros know all too well that chipping and pitching on bentgrass or bermudagrass with excessive grain is really difficult and can make even the best look silly if the leading edge of the club catches the grain before the ball. The more upright the leaves and stems are growing, the better the playing surface for short game shots and the “firmer” approaches will play. These steps can help you manage lateral growth in the approach:

  • Routinely groom and conduct vertical mowing at light intensity and high frequency.

  • For warm-season grasses, scarify approaches with a vertical mower or spring-tine rake and follow with aggressive scalping once or twice annually. Another option is fraze mowing.

  • Routinely brush the approach turf to encourage upright leaf blades and improve mowing quality.
     

Water Management

It is very easy to overwater approaches. There tends to be a lot of overlapping irrigation coverage in these areas and if arcs, nozzles and runtimes aren’t carefully adjusted you can have an excessive amount of water concentrating in a relatively small and very important area. It doesn’t help that most putting greens surface drain into the approaches as well, which adds even more water to the equation. Overwatered approaches are bad for turf health and create a poor playing surface, so careful water management is vital to producing firm approaches. Making a few minor adjustments and keeping a watchful eye on soil moisture can have a big impact on approach firmness in a short amount of time.

  • Adjust sprinkler arcs and nozzles to decrease overspray in the approach as much as possible. It is not always feasible, but try to avoid part-circle sprinklers changing direction over the approach area. A sprinkler will apply 30% to 40% more water on an area during the lag time as it changes direction.

  • Only run approach sprinklers when necessary.

  • Hand water if labor is available. Make this a priority leading up to high-profile events.

  • Utilize portable moisture meters and perhaps in-ground soil moisture sensors to better monitor soil moisture status in the approaches.

  • Make sure that putting green irrigation isn’t generating runoff into the approaches. Not only does runoff mean water is being wasted, it also has a negative impact on playing conditions in front of the green.

  • Drainage also plays an important role in managing moisture in approach areas as we will discuss later in the article.
     

Heavier Mowers and Rolling

Utilizing mowers with heavy down pressure and rolling approaches won’t overcome overwatered turf with excessive thatch, but these techniques will improve firmness on approaches that are already in good condition:

  • Occasionally use heavier fairway mowers to increase down pressure on the approaches. Greater down pressure will yield a better quality of cut. 

  • Roll approaches if your staffing situation allows. At minimum, consider rolling them in preparation for tournaments. While we have not been able to directly correlate rolling to improved firmness, rolling most certainly increases ball roll and therefore makes the approaches play faster. 

Cultural practices can be expected to improve approach firmness to some degree. However, these strategies add complexity and cost to the maintenance operation and may not always produce the desired results. Sometimes, more aggressive strategies may be necessary. 

Part 2 – Renovation Projects to Improve Approach Firmness

While conducting Course Consulting Service visits and working with courses hosting USGA championships, I have observed poor ball reaction on approaches despite a very sound cultural program. When the strategies described in part one do not produce the desired firmness and performance, more-intensive renovation may be necessary. In part two of this article, we will discuss installing drainage and/or replacing the rootzone material in the approach. 

Drainage

Installing a comprehensive network of drainage pipe on tightly spaced intervals will improve turf health and reduce the wet, soggy conditions that lead to soft approaches. Install drainpipes on 10- to 15-foot centers. The tighter the spacing the less risk of chronically wet conditions. Install the drainpipes deep. It is typically recommended to install pipe from 2-4 feet deep to create enough hydraulic pressure and ensure the upper few inches of the soil will dry quickly following rainfall or routine irrigation. There are a variety of pipe sizes and shapes and I recommend reaching out to a soil engineer or company with drainage experience to assist with pipe recommendations. In most cases, backfilling with native soil and gravel will fail the piping ratio and therefore it is recommended to use sand to backfill drainage trenches. Think of the green, approach and surrounds as a watershed and install drainage upslope to capture water before it moves into the approach area. 

Other drainage options include slit drainage, sand-injection aeration and drill-and-fill aeration. Slit drainage has shown good results if tightly spaced. The results from sand injection and drill-and-fill in approach areas are less conclusive. While these strategies may offer turf health benefits, field experience collecting firmness data does not suggest that they improve approach firmness. 

A good drainage network that removes water from the entire approach area will deliver drier conditions, but it does not guarantee the approach will produce the desired ball reaction. The architecture of the rootzone also plays a critical role. 

"Think of the green, approach and surrounds as a watershed and install drainage upslope to capture water before it moves into the approach area."

Replacing the Rootzone

Reengineering the approach rootzone in combination with adding subsurface drainage is an excellent way to improve turf health and approach firmness. When wet, soils with high silt and clay content will be soft and turf health is often compromised due to low porosity, high bulk density and poor water infiltration. It may seem that the best option for solving this problem would be to sand cap the approaches; however, not all sands are created equal. Sand capping with a rounded, uniform sand will deliver good drainage capabilities but will almost certainly yield soft approaches. Consider a trip to the beach. Dry sand with no organic matter has poor stability and is very soft. Closer to the water, the wet sand is firmer due to the cohesive properties of the water. However, it is still unstable and soft because beach sand is typically rounded and the particle size is relatively uniform.

In a golf course setting, a rootzone with rounded sand that is narrowly graded is like that beach sand. It is unlikely to produce a firm, stable surface when wet or dry. Conversely, a rootzone with a more widely graded sand where there is a mix of particle size ranges from very coarse to fine will generally produce firmer surfaces. Adding a small amount of silt and clay to a sand-based rootzone mix will actually improve surface firmness and stability. But how much silt and clay are enough and how much is too much? Finding a balance between material stability, sufficient drainage and soil porosity can be challenging.

Several research projects have helped add clarity to the impact of different rootzone materials on surface firmness and performance. A study completed in 2009 at the University of Connecticut revealed that sand topdressing in fairways improved firmness compared to non-topdressed plots and the application of a finer sand produced greater firmness than coarse sand. 

Another study completed in 2001 at Michigan State University applied civil engineering principles to evaluate the stability of sand materials with different gradation and sand with small amounts of silt and clay added. The bearing capacity (a measure of stability) doubled when the coefficient of uniformity (Cu) of the sand increased from 1.8 to 3.0. All six sands used in this study met USGA Recommendations for a Method of Putting Green Construction. When 10% of a sandy loam textured soil was added to the sand, the soil strength doubled. To recap, the higher Cu sand had twice the soil strength of the low Cu sand and the sand-plus-soil mix had twice the soil strength of the high Cu sand. Despite adding soil, the hydraulic conductivity of the mixture remained greater than 7 inches per hour. The upshot from this study is that a moderate amount of silt and clay (5%-12% of the rootzone mix) can deliver firmer surfaces while still yielding adequate drainage and porosity, depending on the sand and the soil. This is critically important to keep in mind if you’re thinking about sand capping approaches at your course to improve firmness.

"Sand capping with a rounded, uniform sand will deliver good drainage capabilities but will almost certainly yield soft approaches."

Another study recently completed in 2022 at Michigan State University evaluated the influence of rootzone strength and soil water content on inbound golf ball reaction (bounce). Research plots in this study were seeded to a mixture of 80% Kentucky bluegrass and 20% perennial ryegrass and maintained as a simulated fairway. The plots underwent two dry-down cycles in the summer of 2021 and again in 2022. Not surprisingly, ball reaction increased and the depth of the pitch mark decreased as the areas dried. Ball reaction on turf planted in a narrowly graded sand was significantly less than in a widely graded sand and pitch mark depth was greater in the narrowly graded sand. When silt plus clay was added to the widely graded sand at 7%, 9% and 15%, the ball reaction did not differ from the widely graded sand on its own. However, the sand plus silt and clay plots contained significantly higher soil moisture and additional days added to the dry-down period likely would have resulted in increased ball bounce.

Beyond these research projects, there is ample field evidence showing poor ball reaction in areas capped with narrowly graded sands. USGA agronomists have measured firmness and observed ball reaction on approaches during USGA championships for years and have concluded that many sand-capped approaches will not deliver a firm surface and good ball bounce. As an example, a course I worked with in California had some of the best-maintained approaches I have ever seen for a USGA championship. The sand-capped approaches with perennial ryegrass turf contained ideal thatch and organic levels and were rolled daily leading up to and throughout the duration of the championship. The turf water needs were met solely with hand watering using moisture meters. Despite drying down a few approaches to the point of wilt, the ball reaction never met the desired expectations. The approaches never got firm enough because of the characteristics of the underlying sand cap.

On the other hand, the native soil approaches at Pebble Beach for the U.S. Open in 2010, the U.S. Amateur in 2018 and the U.S. Open in 2019 were the firmest I have experienced. The approaches were managed at the highest level, similar to the other course I mentioned, but the native soil delivered far firmer conditions and in many cases the approaches were firmer than the greens.

To sum up this section on changing rootzone characteristics, it is recommended to consider a widely graded, subangular to angular sand and consider adding soil to the sand to yield a mixture containing a small amount (6%-10%) of silt and clay to improve surface firmness and stability. Such a mixture will also deliver far better nutrient and moisture retention than a straight sand, which means less hand watering and faster recovery from stress. It is essential to conduct physical soil tests of all materials to determine the particle size distribution, coefficient of uniformity, hydraulic conductivity, total porosity, and capillary and non-capillary porosity.

Soil physical testing will help reveal the appropriate depth of the rootzone material. The rootzone depth should be determined based on the capillary properties of the material and the goal is to achieve ideal gas- and water-filled porosity. However, these principles are typically determined for rootzones placed on top of a capillary barrier such as gravel. When placed over a native soil, the recommended porosity values of the rootzone may change. A good guideline is to install the rootzone at a depth to achieve a minimum of 10% air-filled porosity in the top 1 inch. A Texas A&M study demonstrated that despite installing a sand cap at a depth that yielded equal air- and water-filled porosity, shallower depths resulted in improved bermudagrass establishment and subsequent management. As the research shows, it is possible to install rootzone material that will yield good ball reaction and still offer adequate porosity and internal drainage. 

Conclusion

A professional golfer who will not be named once asked me if the USGA was intentionally producing firm greens and soft approaches to “trick up” the golf course during a championship. While this was most certainly not the case, I can empathize with his frustration. A front hole location on a firm green with a soft and spongy approach is extremely challenging, even for the best players in the world. The average player has no chance! It pays to implement more rigorous cultural practices in approach areas and in some cases it may be necessary to install drainage and an engineered rootzone to achieve the desired surface firmness and ball reaction. The goal is to optimize turf health while creating a surface that will encourage inbound golf balls to bounce and roll up onto putting greens. This makes golf more interesting and more fun for all players.

If you’re looking for site-specific recommendations to firm-up the approaches at your course, contact a USGA agronomist to get practical recommendations tailored to your facility.